Temp files not deleted on save for spatial addon

### What happens?

I tried to benchmark the spatial Plugin.

With hyperfine I did 13 repetitions.

Each creating a fgb-file.
The open space on drive C: was reduced heavily. Benchmark crashed, when no save left.

Found out that on the Temp dir a copy of each output run was stored und never freed.

See Code:

https://github.com/sehHeiden/geospeed/blob/master/geospeed/duckdb_speed.py

### To Reproduce

"""Test the execution speed for an equivalent of Geopandas Overlay with intersection using a spatial index."""

import time
from pathlib import Path

import duckdb

save_name = None
con = duckdb.connect(save_name if save_name else ":memory:", config={"threads": 15, "memory_limit": "20GB"})
con.install_extension("spatial")
con.load_extension("spatial")

con.sql("DROP TABLE IF EXISTS buildings")
con.sql("DROP TABLE IF EXISTS parcels")
con.sql("DROP TABLE IF EXISTS buildings_intersection")
con.sql("DROP VIEW IF EXISTS intersections")

# Check supported formats for writing
formats = con.sql("SELECT short_name FROM ST_Drivers() WHERE can_create;").fetchall()
print(f"Writable formats: {formats}")
start = time.time()

shapefile_dir = Path("./ALKIS") # Base directory
building_files = list(shapefile_dir.glob("*/GebauedeBauwerk.shp")) # Glob pattern for the subdirectories
parcel_files = list(shapefile_dir.glob("*/NutzungFlurstueck.shp")) # Glob pattern for the subdirectories

# Error handling if no files are found
if not building_files or not parcel_files:
load_error_txt = "No shapefiles found in the provided directory."
raise FileNotFoundError(load_error_txt)

# Create then insert
con.sql(f"CREATE TABLE buildings AS SELECT * FROM ST_Read('{building_files[0].resolve()!s}');") # noqa: S608
con.sql(f"CREATE TABLE parcels AS SELECT * FROM ST_Read('{parcel_files[0].resolve()!s}');") # noqa: S608
con.execute(
"""PREPARE insert_buildings_stmt AS
INSERT INTO buildings SELECT *
FROM ST_Read($1)
WHERE oid NOT IN (SELECT oid FROM parcels);"""
)
con.execute(
"""PREPARE insert_parcels_stmt AS
INSERT INTO parcels SELECT *
FROM ST_Read($1)
WHERE oid NOT IN(SELECT oid FROM parcels);"""
)

# Iterate over the found shapefiles and load them into DuckDB
for building_file, parcel_file in zip(building_files[1:], parcel_files[1:], strict=True):
# Insert into the existing table for subsequent shapefiles
con.execute(f"EXECUTE insert_buildings_stmt('{building_file.resolve()!s}')")
con.execute(f"EXECUTE insert_parcels_stmt('{parcel_file.resolve()!s}')")
# Make the data valid
# Make geometries valid
con.sql("""
UPDATE buildings SET geom = ST_MakeValid(geom) WHERE NOT ST_IsValid(geom);
UPDATE parcels SET geom = ST_MakeValid(geom) WHERE NOT ST_IsValid(geom);
""")

# create indexes
con.sql("CREATE INDEX buildings_idx ON buildings USING RTREE (geom);")
con.sql("CREATE INDEX parcels_idx ON parcels USING RTREE (geom);")
print(f"DuckDB: Loading data takes: {(time.time() - start):.0f} s.")

# Perform intersection
time_intersection = time.time()
con.sql("""
CREATE TABLE buildings_intersection AS
SELECT ST_Intersection(buildings.geom, parcels.geom) as geom,
buildings.oid AS building_oid,
parcels.oid AS parcel_oid
FROM buildings, parcels
WHERE ST_Intersects(buildings.geom, parcels.geom);
""")

# Drop the indexes and unnecessary columns
con.sql("""
DROP INDEX buildings_idx;
DROP INDEX parcels_idx;
ALTER TABLE buildings DROP COLUMN geom;
ALTER TABLE parcels DROP COLUMN geom;
""")

# Create final intersections table
con.sql("""
CREATE VIEW intersections AS
SELECT *
FROM buildings_intersection AS bi
JOIN buildings AS bs ON bi.building_oid = bs.oid
JOIN parcels AS ps ON bi.parcel_oid = ps.oid;
""")
con.sql("""UPDATE buildings_intersection SET geom = ST_MakeValid(geom) WHERE NOT ST_IsValid(geom);""")
print(f"DuckDB: Intersection takes: {(time.time() - time_intersection):.0f} s.")

if not save_name:
# Save the result to a file
time_writing = time.time()
con.sql("""
COPY(SELECT * EXCLUDE geom, ST_AsWKB(geom) AS geometry
FROM intersections
WHERE ST_IsValid(geom) AND NOT ST_IsEmpty(geom))
TO 'buildings_with_parcels.fgb' WITH(FORMAT GDAL, DRIVER 'FlatGeobuf', SRS 'EPSG:25833')""")
print(f"DuckDB: Saving takes: {(time.time() - time_writing):.0f} s.")

print(f"DuckDB: Total duration: {(time.time() - start):.0f} s.")

### OS:

Windows

### DuckDB Version:

1.1

### DuckDB Client:

Python

### Hardware:

30 GB free on C:, Ryzen 5800x 40 GB RAM

### Full Name:

Sebastian Heiden

### Affiliation:

Delphi-IMM, But this usage of DuckDB is private

### What is the latest build you tested with? If possible, we recommend testing with the latest nightly build.

I have tested with a stable release

### Did you include all relevant data sets for reproducing the issue?

Yes

### Did you include all code required to reproduce the issue?

- [X] Yes, I have

### Did you include all relevant configuration (e.g., CPU architecture, Python version, Linux distribution) to reproduce the issue?

- [X] Yes, I have

Start with the linked geospeed/duckdb_speed.py script and reproduce repeated FlatGeobuf saves on Windows, then check the Temp directory for files accumulating across runs. Done means repeated saves no longer leave a growing set of temporary output copies; the issue does not name a project source file or test to start from.

Written by the indexing model from the issue text.